This September 28th will mark 20 years since the founding of Critical Mass in San Francisco in 1992. While Critical Mass remains a controversial subject in its place of birth, it has spread to hundreds of cities in dozens of countries, and become a truly global phenomenon. In September, bicyclists from around the world will be coming to San Francisco to celebrate the anniversary.

To mark the occasion, San Francisco muralista Mona Caron has created a stunning poster, revising her “Bike Angel” character from the poster she created in 2002. Check it out:

Says Mona:

10 years ago I drew a poster for the 10th anniversary of the bicycle movement Critical Mass. Hard to believe it’s been a decade! This mere fact called for a remake. So here’s the sequel: an aged bike sprite with a new generation, plus a little reminder of good old CM etiquette tucked in, and an homage to a random assortment of rad bicycle people from SF and around the world.

If you’ve wandered around San Francisco long enough, you’ve likely spied Mona’s stunning, detailed murals. We wrote about her work back in 2010.

The poster is available to purchase from the sfcriticalmass.org site, and you can also download free jpgs of the image from the associated Flickr page.

Many people know conceptual artist John Baldessari as “the guy who puts dots on people’s faces.” But did you know that he is 6’7″ and that his wifi password is 123456789B? This short documentary tells you all you need to know about Baldessari, crammed into 6 minutes, with gravelly narration by Tom Waits. The film was commissioned by LACMA in 2011 for their “Art + Film Gala” honoring Baldessari and Clint Eastwood, and was directed by Henry Joost & Ariel Schulman.

To commemorate, EFF has produced a special shirt by Robots & Monsters charity demigod Joe Alterio. The shirt looks cool enough under ordinary light conditions, but walk under a black light and super-secret computer codes are revealed. And if you walk into a completely darkened room (where most hackers spend their time), the shirt glows in the dark to reveal a very important message: STRONG ENCRYPTION SAVES LIVES!

Last April, YouTube came up with a new way to help its users understand copyright law. Alleged infringers would be required to watch Copyright School — a short, humorous clip in which everyone’s favorite cartoon characters, the Happy Tree Friends, explain the finer points of copyright law. That’s all good as far as it goes. But the advocacy group Public Knowledge pointed out that the video tended to gloss over an important question for many YouTube users, and that is fair use. Public Knowledge challenged their members to come up with a response video that explains fair use, and how, in some cases, making use of copyrighted material without permission is perfectly legal. Here’s the winning entry, from Patrick McKay:

Awesome cartoonist and free culture activist Nina Paley has produced “Credit Is Due”, another of her great minute meme videos, encouraging those of us who like to share and re-mix the work of others to be sure and give credit where credit is due. Check out Nina’s blog post for more on the subject.

And there’s also Nina’s book Misinformation Wants to Be Free, collecting some of the great comics Nina has used to explore ideas about copyright, free speech and intellectual property.

Last week, the AP reported on a startling find from the Smithsonian Institution: the earliest known color photographs of San Francisco, which also may be the only known color photos of the aftermath of the 1906 earthquake and fire. And they are stereoscopic!

Wait — was there even such a thing as color photography in 1906? In fact there was. The science behind color photography was introduced in the 1850s, and by the early 20th century there were pioneers around the world racing to invent a commercially viable means of bringing photos to life with color. Among them was Frederick Eugene Ives, the man behind the camera that took these images.

Ives’ color process was called “Kromskop” (pronounced “chrome-scope”). Wikipedia’s entry on color photography has some great details:

The color images, dubbed “Kromograms,” were in the form of sets of three black-and-white transparencies on glass, mounted onto special cloth-tape-hinged triple cardboard frames. To see a Kromogram in color it had to be inserted into a “Kromskop” (generic name “chromoscope” or “photochromoscope”), a viewing device which used an arrangement of colored glass filters to illuminate each slide with the correct color of light and transparent reflectors to visually combine them into a single full-color image. The most popular model was stereoscopic. By looking through its pair of lenses, an image in full natural color and 3-D was seen, a startling novelty in the late Victorian age.

The results won near-universal praise for excellence and realism. At demonstrations, Ives sometimes placed a viewer displaying a still-life subject next to the actual objects photographed, inviting direct comparison. A Kromskop triple “lantern” could be used to project the three images, mounted in a special metal or wooden frame for this purpose, through filters as Maxwell had done in 1861. Prepared Kromograms of still-life subjects, landscapes, famous buildings and works of art were sold and these were the Kromskop viewer’s usual fodder, but a “multiple back” camera attachment and a set of three specially adjusted color filters could be bought by “Kromskopists” wishing to make their own Kromograms.

Ives is also famous for his contributions to the halftone reproduction process, whereby photographs are reduced to a series of dots to aid in print reproduction, a technique still used today.